The invention concerns a separation column in microsystem technology for a gas chromatograph comprising a first substrate, a second substrate which is arranged on the first substrate, wherein a trench structure is provided in at least one substrate and the trench structure is sealed off relative to the environment, a stationary phase applied at least to parts of the trench structure, a gas inlet connected to the trench structure, and a gas outlet connected to the trench structure. A further aspect of the invention is a process for the production of a separation column comprising the steps: forming a trench structure in a first substrate, preferably a silicon wafer, applying a stationary phase to at least one portion of the trench structure, preferably by means of polymerisation of a liquid starting material, and sealing off the trench structure by applying a second substrate, preferably a silicon or glass wafer, to the first substrate. Finally a further aspect of the invention is the use of a gas chromatograph in specific areas of use.
Gas chromatographs have been used for some time in chemical laboratories for the analysis of unknown substances and compositions of substances. A new development in the field of gas chromatography is represented by miniaturised separation columns and miniaturised gas chromatographs, as are described for example in patent specifications DE 197 26 000 C2 and DE 103 01 601 B3. Those separation columns and gas chromatographs which are produced using microsystem technology have the considerable advantage that analysis is possible with very small measurement volumes and the entire gas chromatograph is of a very compact structure.
In the case of the miniaturised separation columns an essential feature of the separation column or the separation column production process is that the stationary phase is applied in the form of a layer which is as thin as possible and distributed as uniformly as possible in the separation column. In that respect the problem generally arises that the stationary phase does not achieve adequate mechanical adhesion in the separation column and thus parts of the stationary phase come away spontaneously or during later use of the gas chromatograph. That results in falsification of the measurements and also measurement inaccuracies.
A further problem with miniaturised separation columns in microsystem technology is that the base material of the separation column, that is to say usually the substrate material, has an electrostatic influence which influences the measurement and adversely impairs measurement accuracy. That influence is frequently to be attributed to polarities in the substrate and/or the stationary phase.
Finally a further problem is that the mechanical adhesion of the stationary phase in the separation column diminishes during the operating period of the gas chromatograph and that electrostatic influences of the substrate and/or the stationary phase increase during the operating period. The consequence of this is that the service life of the known separation columns is limited by virtue of the reduction in separation efficiency of the separation column and by virtue of the increase in measurement inaccuracies.